A flight headed to Arizona from eastern Iowa was grounded Wednesday after reports of smoke on board caused an emergency landing.

Pam Hinman, a spokeswoman with The Eastern Iowa Airport, in Cedar Rapids, said a regularly scheduled Allegiant flight from Cedar Rapids to the Phoenix-Mesa Gateway Airport left and returned after reports of smoke in the cockpit.

Krysta Levy, a spokeswoman for Allegiant, said there were 157 passengers on the plane and the smoke resulted from a mechanical issue, and the crew declared an emergency landing "out of an abundance of caution." She said local fire and rescue crews arrived and found nothing unusual.

Hinman said the flight did not last long before being grounded and that there were no reported injuries. At about 1:30 p.m., she said officials were ready to deplane the passengers on board.

Earlier, Twitter user @mrcwillis tweeted that his girlfriend was on board and hadn't been allowed to leave the plane despite smoke making it difficult to breathe. Hinman said she didn't know if there was any validity to that claim.

@Allegiant@KCRG@KWWL Gf is on Allegiant flight CID to Phoenix. Plane took off filled with smoke, landed in CR, emergency crews on the ground. They won't let the passengers leave the plane!